Method for manufacturing a robust tethered ball

ABSTRACT

A method and article of manufacture are disclosed for manufacturing a robust tethered ball. The method includes steps of: (a) providing an elastic tether; (b) cutting the tether to a desired length so that the tether has an end portion that extends from an inner portion of the tether to an end of the tether; (c) folding the end portion of the tether straight back upon the inner portion of the tether so that the end portion of the tether including the end of the tether lies parallel to the inner portion of the tether; (d) securing the end portion of the tether to the inner portion; (e) coating the end portion of the tether including the end of the tether and the inner portion of the tether with an adhesive to provide adhesion between the tether and a liquid polymer; and (f) forming a solid ball on the end portion of the tether from the liquid polymer that completely includes the end portion of the tether, the end of the tether, and the inner portion of the tether.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/813,641 filed on Mar. 29, 2004 for METHOD FOR MANUFACTURINGA ROBUST TETHERED BALL, which is a continuation of U.S. patentapplication Ser. No. 10/319,398 filed on Dec. 12, 2002 for METHOD FORMANUFACTURING A ROBUST TETHERED BALL and U.S. patent application Ser.No. 09/563,305 filed on May 2, 2000 for METHOD FOR MANUFACTURING AROBUST TETHERED BALL, which applications are hereby fully incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is in the field of sporting goods and specificallyit relates to a method for producing a composite article that includes aball and an elastic tether. In a preferred embodiment, the ball has thesize and shape of a baseball, and sounds like a baseball when struck bya bat.

2. Description of Related Art

In the United States, baseball has been a popular sport for well over acentury, and so it is not surprising that a very large number of patentshave been granted for batting practice devices. These devices areintended to permit a sole individual to perfect his swing without theneed to retrieve each ball that is hit. To cause the ball to return tothe vicinity of the batter, it is known to tether the ball to astationary object, such as an upstanding post, a horizontal arm, orother structure.

SUMMARY OF THE INVENTION

In an exemplary embodiment, a method includes steps of:

-   -   (a) providing an elastic tether;    -   (b) cutting the tether to a desired length so that the tether        has an end portion that extends from an inner portion of the        tether to an end of the tether;    -   (c) folding the end portion of the tether straight back upon the        inner portion of the tether so that the end portion of the        tether including the end of the tether lies parallel to the        inner portion of the tether;    -   (d) securing the end portion of the tether to the inner portion;    -   (e) coating the end portion of the tether including the end of        the tether and the inner portion of the tether with an adhesive        to provide adhesion between the tether and a liquid polymer; and    -   (f) forming a solid ball on the end portion of the tether from        the liquid polymer that completely includes the end portion of        the tether, the end of the tether, and the inner portion of the        tether.

In another embodiment, an article of manufacture includes a tetherhaving an end portion that extends from an inner portion of the tetherto an end of the tether. The end portion of the tether is foldedstraight back upon the inner portion so that the end portion of thetether including the end of the tether lies parallel to the innerportion of the tether. The end portion of the tether, the end of thetether, and the inner portion are coated with an adhesive to provideadhesion between the tether and a cured liquid polymer. A solid ball isformed from the cured liquid polymer so that the solid ball completelyincludes the end portion of the tether, the end of the tether, and theinner portion of the tether.

In accordance with one embodiment, a length of elastic shock cord, alsoknown as bungee cord or stretch cord, is used for the tether. The shockcord includes a core of rubber threads enclosed within one or morelayers of braided nylon. In the preferred embodiment, the core of theshock cord is approximately one-half inch in diameter and is surroundedby a single layer of braided nylon.

An anchor is formed at one end of the tether by folding an end portionof the tether back upon the remainder of the tether and fastening theend portion to the remainder by a hog ring.

Next, the end of the tether on which the anchor has been formed isinserted into a mold that will be used for producing the ball. The moldincludes a lower part and an upper part, which are clamped together withthe tether held between them. Each part of the mold includes ahemispherical cavity.

A liquid composed of an activated urethane is poured into the mold toproduce a high density urethane foam. After about 30 minutes, the moldis opened, the ball and tether are removed from the mold, and any roughedges are trimmed off. Thereafter, the ball and tether are permitted tocure for about 24 hours.

The novel features which are believed to be characteristic of theinvention, both as to organization and method of operation, togetherwith further objects and advantages thereof, will be better understoodfrom the following description considered in connection with theaccompanying drawings in which a preferred embodiment of the inventionis illustrated by way of example. It is to be expressly understood,however, that the drawings are for the purpose of illustration anddescription only and are not intended as a definition of the limits ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments described herein are illustrated by way of example andnot limitation in the accompanying figures, in which like referencesindicate similar elements throughout the several views of the drawings,and in which:

FIG. 1 illustrates a perspective view of the shock cord used for thetether after the anchor has been formed at one end of the shock cord;

FIG. 2 illustrates a cross sectional view of the lower part of the moldused to form the solid ball;

FIG. 3 illustrates a cross sectional view of the lower part of the moldused to form the solid ball including the tether anchor of FIG. 1;

FIG. 4 illustrates a cross sectional view of the mold used to form thesolid ball with the upper part of the mold;

FIG. 5 illustrates a perspective view of the solid ball after it hasbeen removed from the mold; and

FIG. 6 illustrates a flow chart for a method of making the solid ball;and

FIG. 7 illustrates a flow chart for a method of making the solid ballwith an adhesive coating to extend wear life.

Elements in the figures are illustrated for simplicity and clarity andhave not necessarily been drawn to scale. For example, the dimensions ofsome elements in the figures may be exaggerated relative to otherelements to point out distinctive features in the illustratedembodiments of the present invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

A serious problem with previous batting practice devices is that theycannot successfully withstand a large number of hits. Depending on thespecific apparatus, the tether may come loose from the ball, the tethermay become damaged and eventually break, or the ball may disintegrate.The use of metal parts, such as a screw eye, is undesirable because ofthe likelihood of damaging the bat. Not only should the tethered ball beable to survive thousands of hits, but also the sound made when the batstrikes the ball should simulate the sound of a real bat striking a realbaseball. Also, the optimum product should be manufacturable inquantity.

The first step in making the tethered ball is to cut the tether to adesired length. In a preferred embodiment of the invention, the tetheris composed of a length of elastic shock cord, also known as a bungeecord or stretch cord. In the preferred embodiment, the cord ismanufactured by the HNW Company of North Vale, N.J., and is designatedas their 0.5 inch single nylon cover bungee cord.

FIG. 1 illustrates a perspective view of the shock cord used for thetether after the anchor has been formed at one end of the shock cord. Itincludes a core 12 consisting of a bundle of strands of rubber. The core12 is surrounded by an inner layer 14 of braided nylon, which, in turnis surrounded by an other layer 16 also of braided nylon. The use of anelectric hot knife is advisable for cutting the shock cord to a desiredlength because it seals the edges of the nylon braid, thereby resistingunraveling. An end portion 18 is bent back 180 degrees, so as to lieagainst the remainder 20 of the length of cord, and the end portion 18is secured in that position by affixing a No. 2 hog ring 22. Thediameter and stiffness of the shock cord used in the preferredembodiment make it impractical to tie a knot at the end of the tether.Also, the size of the knot would make the ball weaker because the ballwould consist of less foam material. In an alternative embodiment, thefolded back end portion 18 is lashed to the remainder 20 of the tetherby a strong cord or wire. The folded back end portion 18 forms an anchor23 that helps to prevent the tether from becoming detached from the ballin use.

The ball 26 is formed by a molding process. For this purpose, a mold,best seen in FIG. 4 is used. The mold includes a lower part 28, an upperpart 30, and plug 32. The lower part and upper part of the mold includerespectively portions 34 and 36 that closely surround and sealinglyengage the outer layer 16 of the tether.

FIG. 2 shows the lower part 28 of the mold. It includes a hemisphericalcavity 38 that defines the size and shape of the ball. To help the ballto cure more evenly, the mold is preheated to a temperature between 80°F. and 100° F. A household electrical bread warmer works well for thispurpose. Next, both halves of the spherical cavity of the mold aresprayed with a silicone mold release liquid, and the prepared shock cordis positioned in the mold as shown in FIG. 3 with the anchor portion 23centrally located within the mold. The upper part 30 of the mold isclamped in place in the position shown in FIG. 4.

FIG. 3 illustrates a cross sectional view of the lower part of the moldafter the prepared tether has been inserted. Shown in FIG. 3 are ananchor portion 23, an inner portion 302 of the tether, an end portion304 of the tether, an end 306 of the tether, an adhesive coating 308, awear resistant coating 310, and an outer portion 312 of the tether.

In FIG. 3, the end portion 304 of the tether extends from the innerportion 302 of the tether to the end 306 of the tether. The end portion304 of the tether is folded straight back upon the inner portion 302 ofthe tether so that the end portion 304 of the tether including the end306 of the tether lies parallel to the inner portion 302 of the tetherto minimize the amount of foam material displaced by the tether. The endportion 304 of the tether is secured to the inner portion 302 of thetether, for example, by crimping a hog ring on the end portion 304. Theend portion 304 of the tether, the end 306 of the tether, and the innerportion 302 of the tether are coated with an adhesive to provideadhesion between the tether and a liquid polymer used to form a solidball around the end portion 304 of the tether. The liquid polymercompletely includes the end portion 304 of the tether, the end of thetether 306, and the inner portion 302 of the tether.

In a preferred embodiment, the ball 26 is composed of a cured highdensity urethane foam. For example, a formulation identified asIPS6168-20F (20 pounds per cubic foot) made by Innovative PolymerSystems, Inc. of Ontario, Calif., has been found to achieve optimumresults. The material is supplied in the form of two liquid componentswhich are stable until mixed. Appropriate quantities of each componentare measured, using 40 parts by weight of component A and 60 parts byweight of component B. These components should be at approximately 80°F. The components are mixed throughly, and a chemical reaction begins.During an early phase of the reaction, the mixture remains pourable, andat that stage the mixture is poured into a pour opening 42 in the upperpart 30 of the mold.

The reaction continues after the mixture has been poured into the mold,and the mixture begins to foam, thereby expanding. The plug 32 of FIG. 4is not set in place until the air has escaped from the mold and foambegins to flow from the pour opening 42. At that point, the plug 32 isinstalled in the pour opening 42. Thereafter, it takes from 15 to 30minutes for the foam to set up so that the ball 26 will hold its shapewhen the mold is opened. During this time, the mold should be maintainedat a temperature of 80°. At the end of this time, the mold is opened andthe ball is removed from it. At this time it is desirable to remove anymold marks from the ball. Thereafter, the ball is allowed to rest atroom temperature for 24 to 48 hours, during which the curing of thematerial is completed. The same process can also be used to produce atethered softball, which is larger than a baseball.

Simple equipment may be used to evaluate the durability of the articleproduced by the above process, for example, a clay target throwingmachine, normally used in trap shooting. The target slinger was replacedby a metal bat, which created a force equal to that employed by acollege level baseball player. The tether was attached to a stand with alength of rubber tubing extending vertically from the stand, surroundingthe tether and supporting the ball. The length of the rubber tubing wassufficient to maintain the tether under a small degree of tension, sothat after each hit, the ball returned to its original position restingon the upper end of the rubber tube. Using this test setup, the ball wasrepeatedly struck by the bat.

As a result of this testing, it was found that the ball and tetherproduced by the above process had a life expectancy in excess of 5,000hits.

The testing also demonstrated that the sound produced when a bat strikesthe ball varies with the density of the cured urethane foam. The mostrealistic sound resulted when the density was between 18 and 32 poundsper cubic foot.

The tether may be, for example, a piece of commercially-availableelastic shock cord having a central core of numerous strands of rubbersurrounded by an inner cover of braided nylon and an outer cover ofbraided nylon. An anchor is formed at one end of the elastic cord byfolding it back upon itself and securing the portion folded back bymeans of a hog ring or by lashing it with wire or cord. A mold having aspherical cavity is used to form the ball, and the anchor portion of thecord is placed in the mold before the mold is filled. A two componentmixture is used, which initially is liquid. The liquid is poured intothe mold, and as the reaction progresses, a foam is formed, preferably ahigh density 100 percent urethane foam. After the foam has set up, thesolid ball is removed from the mold as shown in FIG. 5 and allowed tocure at room temperature.

FIG. 7 illustrates a flow chart 700 for a method of making the solidball with an adhesive coating to extend wear life.

Step 702 is the entry point of the flow chart 700.

In step 704, an elastic tether, for example, a bungee shock cordincluding a bundle of elastic bands (which may or may not be twisted orwoven), in a fibrous sheath, such as a nylon fiber sheath, is providedto make the tethered ball as described above.

In step 706, the tether is cut to a desired length so that the tetherhas an end portion that extends from an inner portion of the tether toan end of the tether.

In step 708, the end portion of the tether is folded straight back uponthe inner portion of the tether so that the end portion of the tetherincluding the end of the tether lies parallel to the inner portion ofthe tether as shown in FIG. 3.

In step 710, the end portion of the tether is secured to the innerportion, for example, by a hog ring, a wire, or a cord.

In step 712, the end portion of the tether, the end of the tether, andthe inner portion of the tether are coated, for example, on theirexterior surface, that is, on the fibrous sheath and the end surfaces,for example, of the elastic bands, in the case when a bungee cord isused, with an adhesive to provide adhesion between the tether and aliquid polymer. The adhesive is preferably absorbed, at least in part,into the exterior surface, so as to further promote adhesion. Theadhesive may be, for example, isocyanate catalyst, which is a mixture ofmethylene bisphenyl dirsocyanate, polymethyleneolyphenol, and methylonebispheylene isocyanate. Preferably, the proportions of the mixture byweight are about 15 percent methylene bisphenyl dirsocyanate, 50 percentpolymethyleneolyphenol, and 35 percent methylone bispheylene isocyanate.

In step 714, a solid ball is formed on the end portion of the tetherfrom the liquid polymer that completely includes the end portion of thetether, the end of the tether, and the inner portion of the tether.Preferably, the liquid polymer is absorbed, in part, into the exteriorsurface, so as to further promote adhesion.

In step 716, a wear resistant coating 310 may be applied, for example,to an exterior surface of an outer portion 312 of the tether thatextends outside the solid ball as shown in FIG. 3. The wear resistantcoating, may be, for example, a mixture of tetrahydrofuran, polyurethanepolymer, and methyl ethyl ketone that is painted or sprayed on the outerportion 312 while stretching the outer portion 312 to increase thesurface area during the application of the wear resistant coating 310.Preferably, the wear resistant coating 310 is absorbed, at least to somedegree, into the exterior surface of the outer portion 312. Preferably,the proportions of the mixture by weight are about 15 percenttetrahydrofuran, 20 percent polyurethane polymer, and 65 percent methylethyl ketone. The addition of the wear resistant coating has been foundto increase the life of the tethered ball substantially.

Step 718 is the exit point of the flow chart 700.

Although the method illustrated by the flowchart description above isdescribed and shown with reference to specific steps performed in aspecific order, these steps may be combined, sub-divided, or reorderedwithout departing from the scope of the claims. Unless specificallyindicated herein, the order and grouping of steps is not a limitation ofother embodiments within the scope of the claims.

The foregoing detailed description is illustrative of one embodiment ofthe invention, and it is to be understood that additional embodimentsthereof will be obvious to those skilled in the art. The embodimentsdescribed herein together with those additional embodiments areconsidered to be within the scope of the invention.

1. A method comprising steps of: (a) providing an elastic tether; (b)cutting the tether to a desired length so that the tether has an endportion that extends from an inner portion of the tether to an end ofthe tether; (c) folding the end portion of the tether straight back uponthe inner portion of the tether so that the end portion of the tetherincluding the end of the tether lies parallel to the inner portion ofthe tether; (d) securing the end portion of the tether to the innerportion; (e) coating the end portion of the tether, the end of thetether, and the inner portion of the tether with an adhesive to provideadhesion between the tether and a liquid polymer; and (f) forming asolid ball on the end portion of the tether from the liquid polymer thatcompletely includes the end portion of the tether, the end of thetether, and the inner portion of the tether.
 2. The method of claim 1wherein the tether comprises a length of elastic shock cord having acore of rubber bands surrounded by a cover of braided nylon.
 3. Themethod of claim 1 wherein the liquid polymer is cured into a urethanefoam.
 4. The method of claim 3 wherein the adhesive comprises anisocyanate catalyst.
 5. The method of claim 1 further comprising a stepof applying a wear resistant coating to an outer portion of the tetherextending outside the solid ball.
 6. The method of claim 5 wherein thewear resistant coating comprises tetrahydrofuran, polyurethane polymer,and methyl ethyl ketone.
 7. The method of claim 6 wherein the wearresistant coating comprises about 15 percent tetrahydrofuran by weight.8. The method of claim 6 wherein the wear resistant coating comprisesabout 20 percent polyurethane polymer by weight.
 9. The method of claim6 wherein the wear resistant coating comprises about 65 percent methylethyl ketone by weight.
 10. The method of claim 1 wherein step (d)comprises securing the end portion of the tether to the inner portion ofthe tether by a hog ring.
 11. The method of claim 1 wherein step (d)comprises lashing the end portion to the inner portion of the tether bya wire.
 12. The method of claim 1 wherein step (d) comprises lashing theend portion to the inner portion of the tether by a cord.
 13. The methodof claim 1 further comprising a step of curing the liquid polymer to adensity of between 18 and 32 pounds per cubic foot to produce arealistic sound when a bat strikes the solid ball.
 14. An article ofmanufacture comprising: a tether having an end portion that extends froman inner portion of the tether to an end of the tether wherein the endportion of the tether is folded straight back upon the inner portion sothat the end portion of the tether including the end of the tether liesparallel to the inner portion of the tether and wherein the end portionof the tether, the end of the tether, and the inner portion are coatedwith an adhesive to provide adhesion between the tether and a curedliquid polymer; and a solid ball formed from the cured liquid polymerwherein the solid ball completely includes the end portion of thetether, the end of the tether, and the inner portion of the tether. 15.The article of claim 14 wherein the tether comprises a length of elasticshock cord having a core of rubber bands surrounded by a cover ofbraided nylon.
 16. The article of claim 14 wherein the liquid polymer iscured into a urethane foam.
 17. The article of claim 14 wherein theadhesive comprises an isocyanate catalyst.
 18. The article of claim 14further comprising a wear resistant coating applied to an outer portionof the tether extending outside the ball.
 19. The article of claim 18wherein the wear resistant coating comprises tetrahydrofuran,polyurethane polymer, and methyl ethyl ketone.
 20. The article of claim14 wherein the liquid polymer is cured to a density of between 18 and 32pounds per cubic foot to produce a realistic sound when a bat strikesthe solid ball.